"E region" is commonly used in reference to the ionosphere, a part of the Earth's atmosphere that extends from about 60 to 1,000 km above the surface. Synonyms for "E region" could include terms like the "E-layer" or the "Heaviside layer," named after British physicist Oliver Heaviside. Other related terms might include "ionosphere," which refers to the entire region of the atmosphere that is ionized by solar radiation, or more specifically the "F region" or "F-layer," which lies above the E region and is even more highly ionized. Meanwhile, terms like "plasmasphere" or "magnetosphere" might be used to describe other related regions above the Earth's surface with distinct plasma or magnetic properties.